Dear Earth Talk:

If humans ruin or outgrow Earth, are there other planets we can hope to colonize?

How
far along are we on efforts to support large numbers of people on the
moon or other planets if our population gets too big or we ruin the
environment here on Earth?

As the human population swells and global warming compounds other environmental problems here on Earth, the notion of colonizing other planets is more appealing than ever. While we are far from being able to support human communities elsewhere in the solar system and beyond, environmentalists are increasingly interested in space exploration as one potential solution to our own earthly woes.

Mars is by far the most promising planet in the solar system on which we could support substantial human life. Currently, Mars is a desolate desert, but the so-called “red planet” once contained liquid water and perhaps harbored life. Many of the elements we depend upon to support life here on Earth, including carbon, silicon, iron and even frozen water, are present on Mars, giving researchers hope that one day some of us could hopscotch through space and set up shop there.

The first challenge of colonizing Mars is transportation. The furthest a manned mission has ever gone to date is the moon, and Mars
is 140 times further away. Currently the biggest hurdle is the cost of
spaceflight. But a new breed of private companies such as SpaceX and
Blue Origin have invested in making launching more efficient by
streamlining manufacturing and even reusing rockets. Elon Musk, CEO of
SpaceX, claims he can reduce the cost of spaceflight 100-fold.

The
best concrete plan for landing humans on Mars is called Mars Direct.
Designed by aerospace engineer and Mars Society founder Bob Zubrin, this
plan was rejected by NASA because it failed to fully utilize new
technologies such as the International Space Station. Zubrin thinks we
could get ourselves to Mars for only $55 billion, which seems like a
bargain compared to the $250 billion figure suggested for a Mars landing
back in 1969 after our first moon landing.

The
most immediate problem for human habitation on Mars is the severe
temperature. The average temperature on the surface of the red planet is
-67° Fahrenheit compared to the balmy 61° here on Earth. Elon Musk
suggests there are two ways to overcome this obstacle. The fast way
would be by dropping nuclear weapons on Mars’ poles, while a slower
solution would entail emitting huge

amounts
of carbon into the Martian atmosphere much as we are doing on Earth but
to a larger extent. In theory, this carbon seeding plan would cause the
atmosphere to grow and eventually shield much of the radiation that
would otherwise be harmful to Martians. Since carbon dioxide is the main
gaseous nutrient consumed by plants, it’s possible that many plants
could thrive on Mars. Without competition, plants could take over the
planet and put oxygen into the atmosphere, eventually making it possible
for humans and other animals to populate Mars without oxygen masks.

There
are still problems with colonizing Mars, however. Its low gravity would
corrode human bones and giant storms rage across the currently barren
planet. In sharp contrast, Earth is rich in resources and water, making
it naturally habitable for plants and animals. Addressing the problems
here on Earth will likely be easier than escaping them by fleeing to
Mars or other planets.